Converts a value to a decimal. If the value cannot be converted to a decimal, $toDecimal errors. If the value is null or missing, $toDecimal returns null.
4.0
https://www.mongodb.com/docs/manual/reference/operator/aggregation/toDecimal/#mongodb-expression-exp.-toDecimal
Converts a value to a decimal. If the value cannot be converted to a decimal, $toDecimal errors. If the value is null or missing, $toDecimal returns null.